The production of meat analogs consist of 2 main stages: emulsion preparation and formation of a chunk. Emulsion is prepared by mixing, chopping and emulsifying a mixture of proteins, salts, fat and other inclusions to form a matrix of proteins that encapsulates the fat and the non-soluble inclusions. The emulsion is then heated under pressure that is aimed in a specific direction. The pressure arranges and orients protein chains and helps the formation of a three-dimensional network. The heat denatures the proteins and sets the matrix in this irreversible form.
Compressive force extrusion processes (also termed extrusion-expansion procedures) for producing meat analogs are known in the art. U.S. Pat. No. 6,649,206 describes a method for producing meat emulsion products with a high level of proteins and a low level of fat. A holding tube and texture enhancement device is used to texturize the products. U.S. Pat. No. 6,379,738 describes the same process, but for product with higher fat content. U.S. Pat. No. 4,125,635 describes a device for texturing protein products which has a typical extruder design. U.S. Pat. No. 6,319,539 describes a method to prepare fibrous food products which mainly comprised of plant proteins (gluten). The foregoing processes have proven unsuitable for making texturized meat products using animal meats rather than vegetable protein sources because of the high shear force exerted on the analog materials. U.S. Pat. No. 4,781,939 describes a method of producing a meat emulsion product in which a heated emulsion is introduced into an elongated tube by centrifugal force while maintaining the emulsion under a pressure greater than the vapor pressure of the emulsion. Upon depressurization, steam forms in the emulsion and disrupts the emulsion mass to form discrete pieces of set emulsion. This type of process is termed “pipe flow” because the meat analog materials flow through the tube as a generally linear stream. The pipe flow processes of the prior art produce relatively low shear force on meat analog materials during processing which makes possible the use of higher amounts of meat derived proteins than compressive force extrusion processes. However, the pipe flow processes and the apparatuses designed to perform these processes have significant problems and disadvantages for food processing. Heat transfer to the transiting meat analog materials is suboptimal and the product chars or burns onto the interior surface of the elongated tube. The prior art pipe flow processes are also limited in that they are not adaptable for use in making meat analogs with a high fat content (i.e. the protein to fat ratio should be at least about 1.5:1). Finally, the processes available in the art are not capable of delivering a meat analog with a high animal protein content and the desired surface texture and appearance of whole meats. Thus, there is a need in the art to address the foregoing limitations to provide improved meat analog products and manufacturing processes.